Field of the Invention
The present invention relates to a wireless power supply technique.
Description of the Related Art
In recent years, in order to supply electric power to an electronic device, contactless power transmission (which is also referred to as “contactless power supply” or “wireless power supply”) has begun to come into commonplace use. In order to advance the compatibility of products between manufacturers, the WPC (Wireless Power Consortium) has been organized, and the WPC has developed the Qi standard as an international standard.
The wireless power supply according to the Qi standard uses electromagnetic induction that occurs between a transmission coil and a reception coil. A power supply system is configured comprising a power transmitter including a transmission coil and a power receiver including a reception coil.
In the Qi standard, a protocol is defined for communication between a power transmitter and a power receiver, which enables information transmission from the power receiver to the power transmitter via a data packet. The data packet is transmitted from a reception coil (secondary coil) to a transmission coil (primary coil) in the form of an AM (Amplitude Modulation) modulated signal using backscatter modulation. The data packet includes electric power control data for controlling an amount of electric power to be supplied to the power receiver.
With conventional communication protocols, such data packets to be transmitted from a power receiver to a power transmitter include only packets that relate to authentication or otherwise an electric power control operation. Examples of such data packets include an electric power control packet, an error indicator packet, a negotiation packet, a received power notice packet, and the like.